I've just been fitting TV aerials in two new houses - one a relative and the other their new neighbour who saw what I was up to and wanted theirs done too, for a few beer tokens..
Both jobs took longer than expected. The first was because the darling builders had managed to get both the coax downleads to have whiskers of braid wrapped round the core in the fitted TV/FM/SAT1+2/Return/Phone socket in the living room. (This is quite nice, incidentally - two downleads feed Sat2 and triplexed Sat1/TV/FM to 2x F connectors and two UHF sockets on the twin faceplate, then a return lead takes your Sky+/ Cable/PVR UHF output back up to a bedroiom socket).
The second time, I was ready for the braid to be all over the place and sorted that out first. Then I tried every combination going (on my own, up and loftground floor in a 3 storey house loads of times) but nothing I tried got a good signal. With my dying gasp I suspected whoever wired it up was even worse than before and tried the 'return' cable, just on the off chance. That was it.
Anyway, on to the point of the post ;-)
While looking for possible failure points, I checked out the (new) aerial closely. The only electrical connections were to two alloy 'horns' near the back which I guess the signal is focussed onto. Or rather, the connections were to a small PCB inside the plastic box the horns came out of. The horns were supposedly attached to the core of the coax by having the PCB screwed down onto them - however the large contact pads that would have touched them was still solidly covered in the non-conductive varnish, and the screws went through the non-plated holes without joining the two together electrically.
I measured to be sure - yup, no continuity. So I scraped some of the varnish off and got a